Shareholders Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 27, 2012	Jan. 28, 2011	Jan. 27, 2012	Jan. 28, 2011	Jul. 29, 2011
Shareholders Equity [Abstract]
Exercise of share-based compensation awards			$ 2,137
Statement [Line Items]
Cash dividends paid (in dollars per share)			$ 0.47
Cash dividends declared (in dollars per share)	$ 0.25	$ 0.22	$ 0.50	$ 0.44
Dividend payment date			Feb. 06, 2012
Change in the fair value of interest rate swap, net of tax	2,412	9,393	6,362	9,576
Accumulated change in fair value of interest rate swaps, net of tax	31,670		31,670		38,032
Share-based compensation expense			5,946
Tax benefit realized upon exercise of share-based compensation awards			$ 155
Preferred stock (in shares)	100,000,000		100,000,000		100,000,000
Common Stock [Member]
Statement [Line Items]
Exercise of share-based compensation awards (in shares)			151,209
Cash dividends declared (in dollars per share)	$ 0.25
Designation of shares of stock as Series A Junior Participating Preferred Stock	300,000		300,000
Preferred stock (in shares)	100,000,000		100,000,000